In inspection using an X-ray computed tomography (CT) apparatus, a positioning scan acquiring a positioning image (scanogram) is performed, in addition to a main scan acquiring a diagnostic image. For example, first, the X-ray CT apparatus performs a positioning scan in a state of stopping rotation of a rotor including an X-ray generator, or while rotating the rotor. Thereafter, the X-ray CT apparatus performs a main scan, with the rotor rotated at preset rotational speed for a main scan. In the case where a positioning scan is performed in a state in which rotation of the rotor is stopped, or in the case where the rotational speed of the rotor in a positioning scan is different from the rotational speed for a main scan, the main scan is not started until rotation of the rotor reaches the rotational speed for a main scan, and the operator and the subject are in a waiting state.